Wafer fabrication is the process by which semiconductor devices are manufactured. It is basically a process by which a silicon wafer substrate is repeatedly coated, etched and rinsed to form such devices. The wafer is then cut to separate the semiconductor devices, which may then be molded into packages for mounting on circuit boards or the like.
Wafer fabrication is a multivariate process and subject to manufacturing defects/variations, however slight they may be. A highly competitive wafer fabrication industry pays a great deal of attention to the occurrence and impact of these defects/variations. In certain situations, such defects/variations lead to the semiconductor devices being scrapped entirely. In other situations, the defects/variations lead to usable devices, but depending on the significance of the defects/variations, for a variety of different high to low importance applications.